Ship for the transportation of a liquefied gas



April 16, 1963 J. J. HENRY 3, 8

SHIP FOR THE; TRANSPORTATION OF A LIQUEFIED GAS Filed June 24. 1958 5Sheets-Sheet l INVENTOR. JAMES J. HENRY ATTORNEYS April 16, 1963 SHIPFOR THE TRANSPORTATION OF A LIQUEFIED GAS Filed June 24. 1958 J. J.HENRY 5 Sheets-Sheet 2 FICI.4-

TY PICA L. INTERMEDIATE WEB FRAME TYPICAL WEB FRAME INVENTOR. JAMES J.HENRY ATTORNEYS April 16, 1963 J. J. HENRY 3,085,538

SHIP FOR THE TRANSPORTATION OF A LIQUEFIED GAS Filed June 24. 1958 3Sheets-Sheet 3 Flq.6

INVENTOR. JAMES J. HENRY AT TORN EYS United States Patent 3,085,538 SHIPFOR THE TRANSPORTATION OF A LIQUEFIED GAS James J. Henry, New York,N.Y., assignor, by mesne assignments, to Conch International MethaneLimited,

Nassau, Bahamas, a corporation of the Bahamas Filed June 24, 1958, Ser.No. 744,164 3 Claims. (Cl. 114-74) This invention relates to a ship and,more particularly, to a ship designed especially for transportation of aliquid cargo which needs to be maintained at a temperature substantiallybelow zero.

This application is a continuation-in-part of my copending applicationSerial No. 582,965, entitled Ship, filed May 7, 1956, now Patent No.3,021,808.

While a ship constructed in accordance with the concepts of thisinvention may be employed for the transportation ofi a wide variety ofdifferent types of liquid cargo which needs to be maintained at anextremely low temperature, the present invention will be described withreference to the transportation of liquefied natural gas in large volumeat about atmospheric pressure, whereby the liquefied natural gas must bemaintained at a temperature below 240 F., depending upon the amount ofheavier hydrocarbons in the natural gas. Methane, which is the principalcomponent in natural gas, boils at a temperature of 258 F. atatmospheric pressure.

Since it will be remembered that the land storage of liquefied naturalgas at substantially atmospheric pressure has resulted in at least onemajor catastrophe due to the failure of the structure supporting thestorage container, some of the problems incident to the design of a shipfor the safe transportation of this same material will be appreciated. v

In hauling liquefied natural gas or methane, hereinafter, forconvenience, referred to as the cargo, some of the unusual factors whicharise may be enumerated as follows: The cargo should be maintained atsubstantially atmospheric pressure since the use of containers withwalls strong enough to maintain the cargo under superatmosphericpressure of any substantial degree would so materially add to the deadweight of the ship as to make such construction economicallyunattractive. Means'must be provided for preventing transfer ofexcessive amounts of heat from the surrounding sea and atmosphere to thecargo to prevent excessive vaporization thereof. The hull of the shipshould be thermally insulated from the cargo so that the latter will notcool the hull, especially when made of steel, otherwise the ship will beunsafe. The tanks or the like means in which the cargo is containedshould be capable of being hydrostatically tested before assembly intothe ship in order toinsure that the tanks will be structurally sound.While the tanks or containers for the cargo should be effectivelyinsulated to minimize the transfer ofi heat, means must be providedwhereby access to such tanks can be had for rapid loading and unloading.Since the individual tanks for the cargo will be subjected to severetemperature changes during loading and unloading, their arrangement inthe ship must be such that they are adequately supported to preventdamage during the voyage while permitting free movement of the tanks inexpansion and contraction without subjecting the ships hull tosubstantial stresses due to the effects of the temperature changes ortemperature graclients which might exist.

By way of further factors relating to the construction of the ship,maximum utilization should be made of the hold space of the ship for thestorage of the liquefied gas; means should be provided for maintainingseparation between the cargo tanks and the ships hull, otherwise theliquefied gas might inadvertently come into contact with the ships hullto cause the deterioration or destruction thereof when, as is usual, thehull is formed of structural steel plate which loses its ductility atthe temperature of the liquefied gas; means should be provided for readyand complete inspection of the walls of the tank and for instrumentationto detect changes in the wall temperatures and the like elements whichwould indicate either breakdown or failure of the insulation or of theliquid cargo tanks; means should also be provided for inspection of thecomponents of the ship and cargo without interfering with the cargospace or the construction of the space, and it would be desirable toenable construction of the ships hull with lesser space taken up byreinforcement, thereby to make more space available for the cargo to betransported. g

It is among the principal objects of this invention to provide a shipstructure which will satisfy many of the FIGURE 3 is a cross-sectionalview in the crosswise 7 direction of a ship shown in FIGURE 1;

FIGURE 4 is a detailed sectional elevational view of the cross-sectionofi the ship below the top deck and illustrating the construction of theship and the hold space therein;

FIGURE 5 is a fragmentary sectional elevational view through -a bulkheadof the ship;

FIGURE 6 is a side elevational view taken along the line 66 of FIGURE 5,and

FIGURE 7 is a sectional view taken along the line 7-7 of FIGURE 4.

The concepts of this invention are embodied in a ship 7 constructionformed of an outer hull 20 having a bottom 22 and vertically disposedside walls 24 and 26 in combination with an inner hull 28 having bothbottom and side walls which extend in closely spaced apart parallelrelation with the corresponding walls of the outer hull throughout themajor portion of the ships length which defines the hold space 30*.

The walls forming the outer hull are reinforced by frames or beams 32which extend lengthwise along the inner surface of the outer hull infairly closely spaced apart parallel relation and by web frames orgirders 34 and 36 which extend crosswise of the bottom and verticallyalong the side Walls of the ship in closely spaced apart relation. Theinner and outer hulls are interconnected by stiffening and reinforcingmembers in the form of tie bars 36a which are secured at their outeredges to the inner face of the outerhull and at their inner. edges tothe outer face of the inner hull, or to the frames fixed in the desiredspaced relation to the adjacent surfaces of the hull members. It will benoted that the thickness of the walls of the outer hull and thedimensions of the beams and frames increase from the top to the bottomof the ship to compensate for the increased loads on the portion of theship displacing water.

The space between the bulls is divided vertically into compartments orwing tanks by a series of vertically spaced apart platforms 38 secured,as are the plates or tie bars, to the inner and outer surfaces of theouter and inner hulls, respectively, or preferably to the frames, as bymeans of welding. The platforms are provided with openings to enablefree communication between the spaced compartments.

Openings 42 are provided in the web frames for ventilation, and accessopenings 44 still larger in dimension are provided in the web frames inthe areas immediately above the platforms to enable a person to travelin a fore and aft direction-the space between the hulls being sufficientfor the passage of a person therebetween.

The space between the hulls is divided laterally by a series of plates,hereinafter referred to as bulkheads 40, which extend upwardlysubstantially continuously from the bottom to the top of the side Wallsto subdivide the space between the inner and outer hulls into aplurality of wing tanks.

The outer surface of the inner hull is similarly stiffened andreinforced with longitudinally extending frames or beams 46 andcrosswise extending ribs. The girders can be used to provide a means forattachment of the interconnecting plates or girders 34 and 36 andinterconnecting tie bars 36a, thereby to effect a rigid and fullyreinforced connection between the inner and outer hulls.

As defined in the aforementioned application, the ships hold can bedivided lengthwise by a plurality of cofferdams which extend crosswisebetween the hulls. In such crosswise extending coiferdams, it isdesirable to make use of a pair of walls 50 and S2 spaced apart by adistance to enable a person to pass therebetween. The describedreinforcing and stiffening beams, girders and plates can also beembodied between the walls to enable access to the space between thewalls and for subdivision of the space into communicating wing tanks.

The inner surface of the inner hull 28 is lined with a relatively thicklayer 54 of an insulating material of low heat conductivity andpreferably characterized by having a'structural strength capable ofsupporting loadto enable attachment to the walls of the inner hull andto enable the cargo tanks to be carried between insulation withoutdirect attachment to the walls of the ship. For this purpose, use can bemade of panels of balsa wood or quippo, or use can be made of foamedglass or foamed plastics which are capable of standing up under thetemperature conditions to which the plastic will be submitted in thepresence of the cargo. The cargo tanks 56 of large dimension are adaptedto be arranged in side by side relation within the insulated hold spaceto'provide a cluster with means harnessing the tanks at the top andoperatively engaging the tanks at the bottom to hold the tanks in apredetermined relation within the insulated hold while permitting freeexpansion and contraction movements in the lateral and verticaldirections responsive to changes or variations in temperature whichmight take place. Thus, the tanks are mounted relatively independentlyof the insulated hold space, but arranged and constructed substantiallycompletely to fill the hold space.

The means for harnessing the cargo tanks is the subject matter ofanother application of Farrell, et al., Serial No. 634,571, filedJanuary 16, 1957, now Patent No. 2,954,003, and entitled Means forTransportation of Low Temperature Liquids. The means for lining thewalls of the inner hull with panels of balsa wood is also the subjectmatter of a still further application of Dosker, Serial No.

646,001, filed March 14, 1957, and entitled Heat Insulated Wall and TankConstruction. The means of constructing the tanks preferably ofprismatic shape is the subject matter of still a further application ofFarrell, et al., Serial No. 634,547, filed January 16, 1957, now PatentNo. 2,982,441, and entitled Liquid Storage Tank. The means for mountingthe tanks to enable expansion and contraction movements is generallydescribed in the parent application to which reference has previouslybeen made.

Referring now to the ships construction embodying the features of thisinvention, technological advancements will be found to have beenincorporated with reference to its use in the transportation of a coldboiling liquefied gas, as represented by a liquid methane (natural gas)carrier. The double-walled arrangement in the hull structure of the shipwith the inner wall lined on its inner surface with a thick layer of athermal insulating material provides a desired separation between theouter hull of the ship and the ships hold to militate against anypossible transmission of the cold from the cargo to the ships hull whichmight otherwise cause destruction of the ship. This enables the outerhull of the ship to be fabricated of steel plate ordinarily used in theconstruction of ships, otherwise it would be necessary to make use ofspecial metals which would not lose their ductility when reduced to lowtemperature. This would result in amateria-l increase in the cost of theship from the standpoint of the metals employed and their assembly, andit would possibly result in reduction of the stability of the ship fromthe standpoint of the strength of the metals employed in itsconstruction.

The construction wtih the inner and outer hulls arranged in closelyspaced apart, substantially parallel relation enables the beamsextending crosswise of the ship and the girders extending lengthwise ofthe ship to interconnect the hulls in a manner which enables the outerhull to incorporate the inner hull as a part of its reinforcement andsupport. This enables increased rigidity and strength to be incorporatedinto the hull structure while making use of beams and girders ofconsiderably lesser width than would otherwise be demanded. This resultsin lesser space being occupied by the beams and girders joined to theadjacent surfaces of the ships hulls so that more space can be madeavailable in the ship, materially to increase the cargo-carryingcapacity of the ship. This condition is not available in a constructionwherein a tank is fabricated within the hold of a ship andinterconnected to the hull for support, since the described parallelrelation and interconnection whereby the inner hull can be tied into theouter hull to enable use of girders and beams of lesser width would notbe secured. Further, the necessity to permit free expansion andcontraction of the cargo tanks will militate against the rigidconnection between the tanks and the hull of the ship.

In the construction with the inner hull arranged in closely spaced apartparallel relation with the outer hull and having girders and ribs inbetween, a fiat and substantially continuous surface is providedthroughout the cargo space of the hold onto which the relaitvely rigidlayers of the substantially strong insulating material can be appliedthermally to insulate the entire hold space in which the cargo tanks areto be arranged. When use is made of a structurally strong insulation,such as balsa wood, for independently supporting the cargo tanks, it isdesirable to enable prefabrication of the balsa wood into boards andplanks which can be applied to the support, and it is also desirable tobe able to incorporate the supporting structure as a backing for theinsulation, whereby the insulation can rely upon its support forstrength. Further, when it is desired to make use of the layer ofinsulation as a second line of defense to block penetration of the coldboiling liquefied gas through the insulation to the metal support, inthe event of failure of the cargo tanks or in the event of spillage ofthe cargo, it

is desirable to be able to make use of the support as a sealing meansalong the outer surface of the insulation layer, whereby a vapor spacewill be built up upon evaporation of the liquid to prevent furtherpenetration of the liquid through the insulation layer. This new andnovel concept of an internally lined container to prevent penetration ofa low boiling liquefied gas which is directly in contact with the porousinsulation is more fully defined in the copending application ofMorrison, Serial No. 692,388, filed October 25, 1957, and entitledInsulated Tank for Storage" and Transportation of Low Boiling LiquefiedGas. The beams and girders ordinarily present as reinforcement andstiffening members in ship construction or in tanker construction wouldbe incapable of providing the desired surface. On the other hand, thecontinuous and fiat surface of the inner hull is ideal for receiving theinsulation lining, thereby to make all of the space within the innerhull and between the cofferdams available as cargo space, therebymaterially to increase the capacity of the ship and utilization of theship as a liquid methane carrier.

The foregoing represents some of the more important technologicaladvances capable of being derived from the combination of closely spacedapart inner and outer hulls, with the inner surface of the inner hulllined with a thick layer of thermal insulating material to provide aninsulated hold space. The double-walled construction can extendthroughout the entire length of the ship, but the important area residesalong the portion spaced inwardly a short distance from the bow and aftof the ship wherein the cargo space is located. Insulated coiferdamsextending crosswise of the ship can provide the desired separation andsupport for the insulation, and the unlined space in the bow and aft canbe employed for housing the mechanism powering the ship and for thestorage of other liquids and fuels or cargo which do not require themaintenance of low temperatures.

A large number of further advantages are available in a tankerconstruction embodying spaced inner and outer hulls with insulationlining the inner surface of the inner hull to provide an insulated holdspace.

The spaced inner and outer hulls, providing a sealing relationtherebetween, enable utilization of the space as wing tanks whereinwater or other fluid can be used as ballast in navigation of the ship.For this purpose, the space can be divided by the bulkheads and the likeinto separate sections to provide separated wing tanks with individualpumping system for handling the fluid. To make most etficientutilization of the ships space, the wing tanks and the like non-cargospaces can be used for the storage of liquid petroleum products which donot require refrigeration or maintenance at low temperature. Forexample, most efficient utilization can be made of the space between thewalls to carry a liquid fuel or petroleum products which can be used asballast and which can be circulated for temperature control and whichcan even be heated when necessary to conduct cold away from the walls.

The spaced relation between the inner and outer hulls enables one toenter the space for visual inspection of the outer walls of the innerhull for purposes of detecting deterioration in the construction insufiicient time in advance to prevent failure which might otherwise leadto difficulties and even to the destruction of the ship. It simplifiesreplacement and repair of sections of the inner hull without tying upthe ship in drydock or the like, and it provides space wherein additionscan be made to shore up weaknesses which might develop in theconstruction to anticipate a dangerous situation which might otherwisedevelop.

Still further, the spaced relationship between the hulls enablesinstrumentation 160 of the ships hulls for automatically recordingchanges in conditions as would provide a warning sufficiently in advanceof the development of a dangerous condition to enable protectivemeasures to be taken. Such instrumentation would record temperaturechanges resulting from the development of cold spots possibly caused bythe failure of a cargo tank or portions of the insulation in particularareas. These are desirable from the standpoint of protection of theouter hull from refrigeration to a temperature where the steels mightlose their ductility and strength.

The closely spaced apart relation between the inner and outer hulls andthe subdivision of the space into wing tanks permits the control oftemperature in the space between the walls to make certain that safeoperating conditions are maintained. In the event of failure of theinsulation or in the event of the presence of liquid cargo outside ofthe cargo tanks in the hold space, the area between the hulls can beheated by means of steam coils and the like to maintain a desiredtemperature condition between the walls. This will prevent thetransmission of cold to the outer hull and it will also operate tomaintain the inner hull at a temperature sufficient to prevent loss ofductility and strength. It will also permit maintenance of thetemperature of the inner hull at a uniform and desirable level forcontrolling heat loss through the insulation. Instead of making use ofthe confined space as a means for heating the walls, the space betweenthe hulls can be used for the rapid circulation of water or other liquidor fluid over the adjacent surfaces of the hulls to conduct cold awayfrom (i.e., furnish heat to) the walls and for controlling thetemperature of the walls to maintain safe and controlled operatingconditions.

It will be understood that changes may be made in the details ofconstruction, arrangement and operation without departing from the spirtof the invention, especially as defined in the following claims.

I claim:

1. A ship for the transportation of a liquid cargo which needs to bemaintained at a temperature far below the freezing point of watercomprising the combination of an outer hull, an inner hull joined to theouter hull and spaced in parallel relation to the outer hull throughoutthe major portion of the ship, horizontally disposed, verticallyspaced-apart stiffening and reinforcing members secured to the innersurfaces of the outer hull and the outer surfaces of the inner hullrespectively, horizontally disposed vertically spaced-apart platformsextending crosswise between the inner and outer hulls and spaced apartby an amount greater than said stilfening and reinforcing members tosubdivide the space between the inner and outer hulls into verticallyseparated compartments, vertically disposed and longitudinallyspaced-apart walls extending crosswise between said inner and outerhulls to subdivide the space therebetween into longitudinally separatedwing tanks, some of said walls having passages therethrough above theplatforms for communication between the wing tanks, instruments mountedwithin the space between the bulls for indicated changes in conditionsexisting therein, bulkheads extending crosswise of the ship inlongitudinally spaced-apart relation to subdivide the space within theinner hull into fluid-tight cargo spaces, panels of thermal insulatingmaterial mounted on the inner surface of the inner hull to line thecargo space with a thick layer of thermal insulating material, and atleast one liquid cargo tank of large dimension within each of saidinsulated cargo spaces.

2. A ship as claimed in claim 1 in which the thick lining of thermalinsulating material lining the inner surface of the inner hull comprisespreformed panels of balsa wood secured at their outer surface to theinner hull to provide a substantially continuous lining thereon.

3. A ship as claimed in claim 1 in which each of the bulkheadssubdividing the cargo space comprises a pair of walls in closely spacedapart parallel relation.

(References on following page) References Cited in the file of thispatent 8 Henry July 28, 1959 Rupp Aug. 4, 1959 Henry Sept. 22, 1959Howard Apr. 26, 1960 FOREIGN PATENTS Great Britain Feb. 27, 1952 OTHERREFERENCES The Oil and Gas Journal, March 22, 1954 (pages 104, 105relied on).

1. A SHIP FOR THE TRANSPORTATION OF A LIQUID CARGO WHICH NEEDS TO BEMAINTAINED AT A TEMPERATURE FAR BELOW THE FREEZING POINT OF WATERCOMPRISING THE COMBINATION OF AN OUTER HULL, AN INNER HULL JOINED TO THEOUTER HULL AND SPACED IN PARALLEL RELATION TO THE OUTER HULL THROUGHOUTTHE MAJOR PORTION OF THE SHIP, HORIZONTALLY DISPOSED, VERTICALLYSPACED-APART STIFFENING AND REINFORCING MEMBERS SECURED TO THE INNERSURFACES OF THE OUTER HULL AND THE OUTER SURFACES OF THE INNER HULLRESPECTIVELY, HORIZONTALLY DISPOSED VERTICALLY SPACED-APART PLATFORMSEXTENDING CROSSWISE BETWEEN THE INNER AND OUTER HULLS AND SPACED APARTBY AN AMOUNT GREATER THAN SAID STIFFENING AND REINFORCING MEMBERS TOSUBDIVIDE THE SPACE BETWEEN THE INNER AND OUTER HULLS INTO VERTICALLYSEPARATED COMPARTMENTS, VERTICALLY DISPOSED AND LONGITUDINALLYSPACED-APART WALLS EXTENDING CROSSWISE BETWEEN SAID INNER AND OUTERHULLS TO SUBDIVIDE THE SPACE THEREBETWEEN INTO LONGITUDINALLY